1. Field of the Invention
The present invention relates to a sensing device, and more particularly, to a waterproof sensing device for a light fixture.
2. Description of the Prior Art
Nowadays sensor-based light fixtures are widely applied to office buildings, business premises, residences, communities, and other public places, and more particularly, to the corridors, stairways, arcades, and other dark areas in need of lighting. By illuminating whenever a motion is detected, the sensor-based light fixture effectively deters potential burglars or thieves at night time and provides enough illumination to surveillance equipments for photographing.
FIG. 1 illustrates a schematic perspective view of a conventional sensor-based light fixture. The sensor-based light fixtures includes a rear casing 10, a first circuit board 12, a second circuit board 14, a frame 15, a lens 18, and a front cover 20. The front cover 20 has a light-output portion 22, which can be an opening. The light source (not illustrated) is automatically activated by detecting ambient light and moving object via the light-output portion 22. The first circuit board 12, the second circuit board 14, the frame 15, and the lens 18 are enclosed by the rear casing 10 and the front cover 20. Electronic components (not illustrated) can be mounted on the first circuit board 12 and the second circuit board 14 to facilitate the operation of the light source. The lens 18 is disposed on the frame 15 and then attached to the inner wall of the front cover 20, i.e., close to the periphery of the light-output portion 22.
In such a case, the edge of the frame 15 compels the lens 18 to be screwed to the front cover 20 around the light-output portion 22 and covers the light-output portion 22 so that the perimeter of the light-output portion 22 is defined. However, with such arrangements, rain drop or moisture is likely to penetrate through the gap between the light-output portion 22 and the lens 18 as well as the joint between the front cover 20 and the rear casing 10. Consequently, the electronic components mounted on the circuit boards 12 and 14 or the light source may be short-circuited or damaged. One approach to address the above problem is to apply seal rings, waterproof adhesives, or other waterproof treatments to the gap or joint of such a structure and the cost is accordingly increased.
Therefore, a waterproof structure for light fixture is highly desired.